roshanvikas@yahoo.com
Stereotactic radiosurgery is the latest technique of radiotherapy in which high dose of radiation is focused on tumor and simultaneously saving the adjacent healthy tissue. Stereotaxy word is originated from Greek and Latin language that means touching the tumor in space. To treat any tumor in body space, we require its three-dimensional coordinates.This coordinate system can be used for ablation, biopsy, radiosurgery, etc.
Stereotactic irradiation uses computer calculated three-dimensional coordinates to deliver a prescribed dose of radiation.SRS can be delivered by Gamma Knife, Cyberknife, X knife (Linear Accelerator).
In our hospital, we are using Linear accelerator for SRS treatment, and it is based on time-tested principles. For SRS main requirement is to make patient still and to shape the beam according to the tumor shape. This beam targets tumor cells and makes them quiescent and with time these tumor cells die.
There are two different techniques, one is SRS, and the other one is SBRT (Stereotactic Ablative Radiotherapy) which is the extracranial extension of SRS.
For SRS technology, the patient requires immobilization, and that is done with a particular type of cast called double shell positioning system, and the patient underwent Contrast Brain MRI and non-contrast CT (reference CT scan) scan that is fused digitally to each
other.
Target, as well as organs at risk, are drawn with the help of special software and beam are placed.This complicated procedure requires around two days.On the day of delivery of radiation again one cone beam CT is taken, and it is matched with reference CT scan, and after checking any error, treatment is delivered. The patient will also require steroids on the day of therapy.
Common tumors that can be treated with this techniques are the Pituitary adenoma, Meningioma, Acoustic Neuromas, Brain metastasis and Recurrent Gliomas.
SRS Is an OPD procedure and is painless, without any incision, and no anesthesia is required.
Author Dr.Vikas Roshan
Consultant Radiation Oncology.
